Conventional methods enable the rolled strip to have a desired finishing temperature and a desired final thickness.
The quality of the rolled strip is, however, not determined exclusively by these variables. Furthermore, the variables determining the quality of the rolled metal strip are, for example, the profile, the contour and the surface evenness of the metal strip.
The terms profile, contour and surface evenness are to some extent used with different meanings in the prior art.
For example, in the actual lexical meaning, profile means the progression of the thickness over the width of the strip. But according to prior art the term is used not only for the progression of the thickness of the strip over the width of the strip but also sometimes as a purely scalar dimension for the deviation of the thickness of the strip at the edges of the strip from the thickness of the strip in the center of the strip. The term profile value is used for this value in the following.
The term contour sometimes means the absolute progression of the strip thickness, sometimes the absolute progression of the strip thickness less the thickness of the strip in the centre. The term contour progression is used in the following to mean the progression of the strip thickness less the thickness of the strip in the center of the strip.
In its lexical meaning, the term surface evenness includes mainly only visible deformations of the metal strip. According to prior art, and also in the context of this invention, it is however used as a synonym for the internal stresses in the strip, regardless of whether or not these internal stresses lead to visible deformations of the metal strip.
According to prior art, different methods for the control of the surface evenness of metal strips are already known. One such method is, for example, known from DE 198 51 554 C2. However, these methods do not work completely satisfactorily. In particular, the pre-setting and the maintenance of a preset surface evenness is sometimes difficult.